A longitudinal and experimental study is designed to provide a fuller understanding of the variables involved in a family's coping with leukemia in a child. Using multi-source and multi-method data to obtain behavioral components of coping, families will be studied over a five-year period from the time of diagnosis throughout the process. Analysis of this data will include both individual emphasis for each family and group comparisons. The theoretical framework is healthy coping, rather than a pathologic orientation. All leukemia families and a random selection of non-leukemic families will be studied, and assessed over time. In addition, the families will be randomly assigned to three groups (same for non-leukemics) to assess the impact of an intervention by a mental health professional which is designed specifically to help families cope with leukemia in a child: 1) total intervention; 2) moderate intervention; and 3) no intervention. The non-leukemia families will provide a control for comparison of coping processes. Through clinical interviews, systematic observational methods, and psychological assessment, relationships among coping, degree of prior functioning, demographic and background data, and interactional data will be studied. Analysis of the data will include time-series methods for individual families, multiple regression to determine predictors of coping, analyses of covariance to assess the effects of the intervention and correlational and nonparametric methods where indicated by the data.